One conventional semiconductor structure includes a substrate and at least one chip or die. The chip is located on the upper surface of the substrate and electrically connected to the substrate. The substrate is an organic substrate and includes at least one metal layer and at least one dielectric layer. Typically, the coefficient of thermal expansion (CTE) of the metal layer is different from that of the dielectric layer. Hence, the substrate is subject to warpage after the substrate is heated and then cooled. Placing a metal ring on the upper surface of the substrate can confine the deformation of the substrate to thereby reduce or prevent warpage.
However, the conventional semiconductor structure with the metal ring has shortcomings. When the metal ring is made of aluminum (Al), the warpage of the substrate can be effectively reduced. However, the CTE of aluminum is rather large, and the deformation degree of aluminum is relatively high, thus potentially leading to delamination of the metal ring from the substrate. By contrast, when the metal ring is made of copper (Cu), the CTE of copper is rather small, and the deformation degree of copper is relatively low. As such, delamination is less likely to occur between the copper ring and the substrate. Nevertheless, the substrate is still subject to warpage, and so is the metal ring.
A solution to the foregoing warpage issues would be of great benefit to the semiconductor industry and its customers.